Road working apparatus



` Aug. 24, Y1954 w R DAY 2,687,071

ROAD WQRKING APPARATUS Filed April 23. 1952 INVENTOR. 46 W/L/AM A my @'73 Www @M-4 Patented Aug. 24, 1954 UNITED STATES PATENT OFFICE ROAD WGRKING APPARATUS William P. Day, Cleveland Heights, Ohio Application April 23, 1952, Serial No. 283,958

3 Claims. l

The present apparatus relates to improvements in road working apparatus and more particularly to improvements in vibrating and tamping apparatus used in the building of roads and like structures.

In the construction of roads and other like surfaces a base is `usually built comprising coarse aggregate material such as broken stone, slag and the like lled with fines or screening of similar materials, the base usually being built up to a desired thickness by two or more courses of lled aggregate, For some purposes, the filled aggregate structure itself is used for roadway or other surfaces supporting vehicular traffic and in other cases a bituminous surface or concrete surfacing is applied thereto. Whatever the ultimate nnished form or the number of courses used the procedure in laying any given course is generally the same. The coarse aggregate is spread to a certain thickness and compacted by rolling, tamping, vibrating or other like procedures. Fines are then spread thereover and dispersed into the aggregate layer to fill the interstices thereof by tamping, rolling or vibrating operations, and, finally, the Whole thickness is finally worked to the desired dimension and density by further compacting operations.

Various compacting apparatus have been used heretofore, such as the long used steam roller or the more recently introduced tamping and vibrating mechanisms. In my (zo-pending U, S. application, Serial No. 5,388, filed January 30, 1948, now Patent No. 2,633,781, a new and improved apparatus for such purposes has been disclosed which produces both a tamping and vibrating action on the materia1 being worked. The apparatus therein disclosed has been successfully used to lay very thick bases of superior density as a single course of aggregate well filled with fines, in other words, bases of such thickness as hitherto it has been practical to construct only in two or more courses.

In such vibrating and tamping apparatus, particularly such as that disclosed in my aforementioned` application, the present invention aims at improvements which result in greater and more uniform compaction densities with fewer passes of the apparatus over the surface being treated. The invention here disclosed comprises the combination, with the tamping and vibrating mechanism of a compacting machine, of` means for statically loading the vibrating mechanism which includes an elastic suspension or support therefor.

The general object of this invention is the provision in a road working machine of mechanism of the tractor unit of the machine.

of the vibrating, tamping type having improved compacting action. Another object is the Drovision in a road working apparatus of a vibrating and tamping mechanism having static loading means elastically supported thereon. Other objects and advantages of the invention will appear from the following description of a particular embodiment thereof and the drawings wherein- Fig. 1 is a side View of a vibrating and tamping unit of a road working machine having the loading means of this invention;

Fig. 2 is a plan view of the unit of Fig. 1; and

Fig. 3 is a fragmentary section showing details of the pivot mounting provided for the static loading means.

Though not so limited in application, this invention is shown in the drawings as embodied in a road working machine such as that disclosed in my above mentioned co-pending application, but only a transverse shoe supporting means IIl of the tractor machine and a single vibrating and tamping sho@l and mechanism II are shown for the sake of simplicity. Preferably a plurality of tamping shoes II are disposed across the front Each shoe I I is connected resiliently at each side to an arm I2 by a vibration damping unit I 3, and the arm in turn is pivotally supported by a bracket structure carried by the beam It through a set of damping units I4 and pivot shaft I da so that vibration induced in the tractor unit by the shoe II is minimized. Not shown in the drawings is a retracting or elevating mechanism where-by the entire shoe mechanism I I may be swung up from the ground about the horizontal transverse pivot shaft Illa when the vibrating mechanism is not in use. Each of the damping units I3, I4 is similar in structure to unit 38 or 39 shown in Fig, 3 and hereinafter described.

To impart to the entire shoe mechanism II the desired vibrating and tamping motion, an actuating unit I6 is provided thereon. Preferably this actuating unit is of the type described in my aforementioned application, having a pair of similar meshing coplanar gear wheels Il, I 8, each provided with an eccentric mass I9, and driven at identical speeds in opposite directions, with the rotational relation of the weights I9 being such as to develop a reaction force vibrating the shoe in a desired direction, for example that of the straight arrow in Fig. l. To minimize horizontal force components transmitted to support I0, the wheels Il, I8 are mounted on parallel shafts 20 disposed in a plane preferably near parallel to the plane of the supporting arms I2 and the eccentric weights I9 are disposed so that their mass centers will pass simultaneously through the plane of the shafts developing a force resultant midway between the wheels and perpendicular to the plane of shaftsI 20. External to the housing of the actuating unit I6 a pulley 2|, mounted on the projecting end of the shaft 2l) supporting wheel I8, is driven through belting 22 by a pulley 23 mounted on a drive shaft 2li, which is supported by the transverse beam I and in turn driven by an engine carried on the tractor.

On the top plate 3|] of the actuating unit I6 a pair of bracket plates 3l is provided pivotally mounting, in a manner hereafter described, the bracket arms 32 of the loading weight or mass 33, the transverse horizontal pivot'axi's of the weight being disposed parallel to shaftsHZll-and above and intermediate the ends of the arms l2. The weight 33 is located or centered in the line of action of the reaction force resultant of the wheels, rthat is, the mass center thereof lies in the common plane of rotation ofthe mass centers of the eccentrically weighted coplanar wheels. The heavy helical spring 34 is interposed between the top plate 36 andthe mass 33. To maintain this spring in proper position, one end is inserted `within a recess 35 bored in the bottom Vof the-static loading mass with the other end restingl on a block 36 on top plate 3i] of the actuating unit housing. Block 35 also may be recessed or provided with other means for maintaining the lower end in position. To provide a restrained, resiliently pivoting mounting for the mass 33, the pivotal connection betweenthe brackets 3l and 32 at each side of the mass is provided by the structure shown in detail in Fig. 3. The brackets 3l, 32 are provided-respectively with rubber mounting units 38 and-39 similar to the units i3 and I4. Unit Sfcomprises an outer cylindrical collar 46 aiiixed to the bracket plate 3i, an inner sleeve 42, and a' cylindrical rubber cushion ill betweenand bonded to the` outercollar and inner sleeve. Unit 39 comprises a like collar d3 -on bracket plate 32,l cushionfll and sleeve d5. Between the inner sleeves 52 and 45 of each pair of units 33, 39is inserted a'spacing washer fit. Likewise a spacing tube i8 is interposedbetween the inner sleeves 42 rof two units 38. A rod lil, extending through the four inner sleeves 12, l5 and spacing tube d8, is provided at each threaded end with washer i9 and nut wherebyrthe several inner sleeeves and-spacersweight away from Vcoil spring 34 during dynamic i operation of the shoe. With the mounting structure shown the cushions may be adjusted to prestressed condition `to increase the resistance to upward swinging of the weight.

In one` application of this invention siXshoe' units of the type shown in` the"drawings were mountedv on beam iti across-the front of a tractor unit. "shoe, about' -2l feet long andv l/g i'eet wide and weighing about 580'poundS-includ'- ing'the static loading-weight 33 of about-160 pounds,`was provided with a pair of rotors I1, i8"

inducing aboutdlOO poundsforce at ya vibration rate oi'2200 V. P. M. and a shoe liftfof--about'v inch.: Over operating rangesv of 200G-2800"#v Hence the V. P. M. and 16 to 45 feet per minute forward travel of the tractor corresponding to about 1 to 6 second duration of local contact, gravel courses as great as 12 inches in compacted thickness have been worked with compaction efficiencies increased from 50 to 90% above that attained without the spring supported static loading weight. Hence the area that may be compacted in a given time is materially increased and greater compaction densities' may be obtained as compared with'prior apparatus of similar type.

rrhe individual shoes in the six-shoe apparatus-described above vibrated up and down beneath the static loading weights which remained substantially stationary due to inertia, the spring 34 beingcompressed on the upward swing storing energy which is available to increase the eiect of 'the 'downward compaction stroke. The shoe maintained ground contact at all times during a vibration cycle, Irocking slightly about the axis of mounting .i3 -positioned behind the line of action of the force resultant of the unbalancedA wheels by virtue ofthe resilient torsional freedomA hicle; aA sho`estructurehaving a surface adapted tovslide on the ground; an arm structure carrying the shoe and pivoted to the vehicle on a horizontal axis for mounting the shoe on the vehicle; for movement lrelativethereto in a vertical plane parallel tothe direction of vehicle movement; a

pair of similar eccentrically weighted gear wheels 1 mounted-on' the shoe by transverse shafts and' meshed to rotate at equal speeds in opposite senses,` the shafts oisaid wheels being mounted parallel-in a common plane which'is substantially' parallel to the centerline of said arm when in operative position' and the" eccentric weights of the wheels-being oppositely rotationally positioned relative to'each other to substantially counterbalance one another in the directionk parallel to the centerline ofv said arm, whereby when the'whe'els lare rotated at high speeds the major force components ydeveloped by the eccentrically` weighted wheels act in a direction generally normal to thecenterline of said arm; means for driving the unbalanced wheels;- a loading weight resiiiently supportedI on-said shoe and centered above saidwheels with its center of massin' a line normal-tothe plane throughsaid shafts andmidway therebetween;A transversepivot means on theupper portion of said shoe pivotally. supportingsaid' mass onsaid shoe,V said pivot means includingfresiiient bushings operatively disposed between saidl weight and shoe to restrain upward movement of said weight relative to` said shoe,

the restraint `increasing-withincrease of said upwardl movement; and `compression spring means resiliently supporting'saidweight onA the shoe,-the axigf'of' said spring meansfbeing disposedin the said normalk line.-

2': A" road base cempactin'g vapparatus 'comprising #atractor-rnachine; a shoe structure having "al bottomsurf'ace 'adapted for support vby'an'd sliding engagement -wit'h'fthe surface' of a road vvbase; an arm carrying the'shoe "andl pivoted to the tractor machine on`- afhoriuontal-faxis for vertically rvmov ably mounting the shoe thereon, said arm being inclinedlrelativev 4to-"theroad base surface f' when in shoe operating position; an actuating mechanism mounted on the shoe for vibrating the shoe in a plane normal to the road engaging surface of the shoe and parallel to the direction of movement of said tractor machine, said mechanism comprising two similar coplanar eccentrically weighted meshing gear wheels mounted on the shoe by transverse parallel shafts lying in a plane which is substantially parallel to said arm when in operative position, the wheels being meshed with the mass centers thereof oppositely rotationally positioned relative to each other so that the forces created by rotation of the wheels are additive in a direction generally normal to the said arm and opposed in a direction parallel thereto; and loading means for the shoe including a weight resiliently supported on said shoe and centered above said wheels with its center of mass in a line normal to the plane through said shafts and midway therebetween, said weight being carried by a second arm pivotally mounted to said shoe with the pivot axis disposed above and transverse to the rst said arm, pivot means mounting the second arm to said shoe including a torsionally resilient element torsionally stressed by movement of the second arm to yieldingly restrain movement of said weight away from said shoe,

6 and compression spring means interposed between the weight and the shoe structure coaxial with said normal line supporting the weight relative to the shoe.

3. A road base compacting apparatus as described in claim 2, including a plurality of said shoes with corresponding shoe mounting arms in parallel relation across the front of said tractor machine, a beam member extending across the front of and fixed to the tractor having pivot brackets pivotally mounting the shoe arms for independent vibratory movement of the shoes, power means on the tractor for driving the shoe actuating mechanisms, and mechanical power transmission means connecting the power means and actuating mechanism of each shoe.

lfeierences Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re.20,663 Cameron Mar. 1, 1938 1,955,101 Sloan Apr.. 17, 1934 2,160,462 Schieferstein May 30, 1939 2,293,962 Baily Aug. 25, 1942 2,599,330 Jackson June 3, 1952 

